fact_get

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are supplied, so the description carries the full disclosure burden. It does add genuinely non-obvious behavior, namely the as_of default of 'now' and the fact that validity is evaluated at that timestamp, but it never states that this is a read-only operation, says nothing about result shape, ordering, or volume, and gives no permission or failure context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences with no filler, and the default behavior is stated inline where it is needed. The telegraphic phrasing ('Omit predicate for all of them') is dense but not wasteful, though it reads more like notes than a front-loaded statement of intent.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no annotations and no output schema, the description is the only place an agent can learn about this tool, and it covers inputs well but leaves the return side entirely unaddressed. For a query tool with four parameters, an agent still cannot predict whether it receives one value per predicate, a list of statements, or how conflicts across sources are resolved.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must supply the meaning itself, and it does for three of the four parameters: as_of with its default, predicate with the omit-for-all semantics, and project with its narrowing scope. Only subject is left undefined, and its meaning is self-evident from the name.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description identifies the resource (facts about a subject) and the qualifying dimension (valid at a given as_of), which is enough to distinguish a temporal point-in-time read from a plain lookup. It stops short of naming the sibling it differs from (fact_history for history, fact_set for writes), so the differentiation is inferential rather than explicit.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Guidance is limited to parameter-level branching: omit predicate to get all facts, supply project to narrow to one project's timeline. There is no statement of when to prefer this over fact_history or fact_set, and no prerequisites or exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.